parze 0.5.1

A clean, efficient parser combinator
Documentation

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Parze

Parze is a clean, efficient parser combinator written in Rust.

Example

A parser capable of parsing all valid Brainfuck code into an AST.

use parze::prelude::*;

#[derive(Clone, Debug, PartialEq)]
enum Instr { Add, Sub, Left, Right, In, Out, Loop(Vec<Instr>) }

parsers! {
    bf = {
        ( '+' -> { Instr::Add }
        | '-' -> { Instr::Sub }
        | '<' -> { Instr::Left }
        | '>' -> { Instr::Right }
        | ',' -> { Instr::In }
        | '.' -> { Instr::Out }
        | '[' -& bf &- ']' => |ts| { Instr::Loop(ts) }
        ) *
    }
}

Features

  • All the usual parser combinator operations
  • Macro for simple rule and parser declaration
  • Support for recursive parser definitions
  • Custom error types - define your own!
  • Prioritised / merged failure for more useful errors
  • No dependencies - fast compilation!
  • no_std support

Why Parze?

Parze is fast and lightweight, acting as a bare-bones framework upon which more verbose and interesting parsers can be constructed (see the custom_error example).

Performance

Here are the results of a JSON parsing test when compared with pom. More performance metrics to come later.

test parze ... bench:   5,275,399 ns/iter (+/- 653,539)
test pom   ... bench:  18,843,978 ns/iter (+/- 2,602,971)

Explicit Form

While Parze encourages use of macros for much of its declarative notation, it is possible (and often useful) to make use of the more explicit rust-y notation.

Here is the Brainfuck parser given above, declared in explicit form.

let bf: Parser<_, _> = recursive(|bf| (
        sym('+').to(Instr::Add)
    .or(sym('-').to(Instr::Sub))
    .or(sym('<').to(Instr::Left))
    .or(sym('>').to(Instr::Right))
    .or(sym(',').to(Instr::In))
    .or(sym('.').to(Instr::Out))
    .or(sym('[').delimiter_for(bf).delimited_by(sym(']')).map(|ts| Instr::Loop(ts)))
).repeat(..));

License

Parze is distributed under either of:

at the disgression of the user.